Contrary to what you might think this chipset was not fully supported until recently, when code submitted by Vojtech Pavlik was incorporated into the 2.4.19-pre9.patch . None of the kernels that you can emerge through portage have that patch, so if you want full support for that chipset you have to build your own patched kernel. Keep in mind that this patch is a work in progress.

So what you need to do is emerge vanilla sources, then head over to ftp.kernel.org get 2.4.19-pre9.patch and apply that patch to the vanilla sources.

Optionally you can also get the pre-emptive kernel patch and apply that AFTER you applied the patch mentioned above.

I did this and my system (Soyo Dragon +, kt266a/VT8233CE) runs smoother than ever:)